There is no reason for him to 'improve' his RPB any more as it fits into his game fine as it is. And for someone like Xu Xin who is very confident in forehand to forehand loop rallies, he shouldn't be trying to change his style of play at all. I don't think his forehand will ever hold him back, plus he's doing very well at the moment isn't he and it looks to continue.
Yes there is, maybe not right now, but in the future. You think he can still be running around and hitting 90% forehand shots when he is over 30? I think not.